Myocardial Infarction - Acute - Wavy Fibers

An early morphologic change in acute myocardial infarction is the appearance of wavy and thinned fibers.The first image shows a low-medium magnification of a section of myocardium. The central area of the image shows wavy fibers (myocytes).

The second image is a higher magnification of the wavy fibers. Note that in addition of being wavy, they are also thinner in diameters than the adjacent non-wavy cardiac myocytes (fibers). The nuclei are not piknotic and show no karyolysis.

The lower image shows, in addition to wavy fibers some capillary congestion in these areas. There is a distinct lack of polymorphonuclear infiltration.

The last image at the bottom shows an area of thinned wavy fibers which are also hypereosinophilic and concomitantly there are myocytes sowing contranction bands.